Different mechanisms of spin reorientation in exchange coupled double rareearth-transition metal layers with in-plane and perpendicular magnetic anisotropy

The objective of this article is to clarify the spin reorientation effects in exchange coupled layers based on rare earth and transition metals with i n-plane and perpendicular anisotropy. These systems are proposed for high d ensity magneto-optical recording with super resolution readout. Two mechani sms are found to be responsible for this change of the magnetization direct ion with the temperature. The first mechanism is an intrinsic spin reorient ation in the GdFeCo layer and the second is the exchange coupling force bet ween the perpendicularly magnetized TbFeCo film and the in-plane GdFeCo fil m. With appropriate adjustment of the compensation temperatures and the thi cknesses of the films, it is possible that the one or the other mechanism d ominates. The experimental results are in agreement with a numerical calcul ation of the magnetization profiles in the coupled system. (C) 2000 America n Institute of Physics. [S0021- 8979(00)34708-9].